1. Field of the Invention
The present invention relates to a data processing device with a keyboard having pop-up keys.
2. Description of the Related Art
Data processing devices such as laptop computers and word processors have become very popular in recent years because their small size and light weight makes them extremely portable. Many attempts have been made to improve the keyboard of these devices to give them an even slimmer shape.
Japanese Patent Application (KOKAI) No. HEI-5-298000 describes a keyboard device including a flat spring sheet; keys each having a restoration spring and a contact depressing spring formed integrally on the flat spring sheet; and a sliding mechanism having an eccentric cam, a stud, and a suspension spring. The sliding mechanism links the flat spring sheet to an openable lid so that the flat spring sheet slides with opening and closing movements of the lid. When the flat spring sheet is slid by the sliding mechanism, the height of the keys is changed by the restoration spring and the contact depression spring. The spring sheet slides in association with rotation of the eccentric cam and changes the level of the keys accordingly so that an operator can freely change the level of the keys by adjusting the angle to which the lid is opened.
However a drawback of this mechanism is that an operator cannot adjust the lid to a desired angle without also changing the level of the keys. Because a liquid crystal display (LCD) is usually provided to the lid, an operator must be able to adjust the angle of the lid to an angle where he or she can see the display of the LCD. The angular range at which LCDs can be viewed is narrow, for example, narrower than that of cathode ray tubes (CRTs). Also, the viewing angle of LCDs depends on the amount of external light. Because laptop word processors are meant to be portable, they are often used in various places, each with different light conditions. This further increases the requirement that the lid be freely adjustable to any angle.
In this way, the mechanism described in Japanese Patent Application (KOKAI) No. HEI-5-298000 has conflicting problems. When an operator adjusts the angle of the lid to where he or she can see the display of the LCD, the level of the keys will change, possibly to a level where operating the keys is difficult. On the other hand, if the operator adjusts the lid to an angle where the keys are easiest to operate, he or she may not be able to see the screen of the LCD.